Hi,
Yes, you can use the contact form:
www.hikashop.com/support/contact-us.html
A user account will be helpful if it is needed. However, from what you're saying it seems that you need to login to access the shop ? In that case, it means you probably already have an address linked to the account, no ? In that case, the tax would be calculated based on that address and not the "main tax zone" of your HikaShop configuration. That would explain why it doesn't work like you want.
Also, we got your message with the user account, but you didn't provide the URL to access the website. Could you provide that too ?
In the "main tax zone" setting, you can and should only select one zone. The zone you want to be used for tax calculations when the current user doesn't have an address yet. So it should either be a zone linked to a tax rule (a state in UK) if you want the prices to be taxed on your products listings, or a zone not linked to a tax rule (another country zone) if you don't want the prices to be taxed on your products listings.
That means anyone signing up from the channel islands will not find their state?
The list of states you see on the registration form depends on the country selected by the customer, and before he selects one, or if you disabled the "address country" field, it's the "default" value of the address country field which is used to get that list, not the main tax zone.